Insulating connector rods and their methods of manufacture

ABSTRACT

Methods for manufacturing highly insulating connector rods and highly insulating composite wall structures using such connector rods. The connector rods are highly insulating and are injection molded in a single step from an appropriate resinous material or moldable plastic. Discontinuous fibers may be impregnated within the resinous material or other moldable plastic. The single-step molding method yields connector rods having pointed ends for facilitating entry through an insulating layer and a first structural layer not yet cured, and also an enlarged head for receiving an impact from a hammer or mallet or for facilitating gripping by the installer. The enlarged head also provides an anchoring effect within a second structural layer upon curing. The connector rods are manufactured to include a ridge or flange to limit the depth of penetration by the connector rod when inserted into the insulating material when forming the composite wall structure. The ridge or flange also helps to prevent the collapse of the second structural layer towards the first structural layer after formation of the composite wall structure and implementation at a building site.

BACKGROUND OF THE INVENTION

1. Related Applications

This application is a division of U.S. application Ser. No. 08/526,805,now issued U.S. Pat. No. 5,830,399, entitled "Highly InsulativeConnector Rods and Methods for Their Manufacture and Use In HighlyInsulated Composite Walls" and filed Sep. 11, 1995, in the names ofDavid O. Keith and David M. Hansen, which is a division of U.S.application Ser. No. 08/225,910, filed Apr. 8, 1994, now issued U.S.Pat. No. 5,519,973, which is a continuation-in-part of U.S. Designapplication Ser. No. 29/011,867, filed Aug. 17, 1993, now issued U.S.Design Pat. No. D 357,855. For purposes of disclosure, the foregoingpatents and applications are incorporated herein by specific reference.

2. Field of the Invention

This invention relates to highly insulative connector rods used tosecure together multiple layers of material within a composite wallstructure. In particular, the high shear strength connector rods have ahigh R value and are used to join together a highly insulating layersandwiched between concrete layers on either side of the insulatinglayer.

3. The Relevant Technology

As new materials and compositions have been continuously developed,novel methods of synergistically combining apparently unrelatedmaterials to form useful composites have also been developed. This istrue of the area of building and construction in which high strengthstructural walls have been fabricated and then coated or layered withhighly insulative materials having relatively low strength to provide astructure of both high strength and high insulation. In general, thestructural component is built first; thereafter an insulating mat isattached to the structural component. More particularly, an outer wallstructure is erected, an insulating material is placed on the inside ofthe outer wall structure, and an inner wall is placed over theinsulating material to protect and hide it. The purpose of theinsulation is to prevent, or at least slow, the transfer of thermalenergy between the inner and outer walls. A commonly used measurement ofthe thermal insulating qualities of a material is the mathematicalcoefficient "R." As used in the art, the coefficient R is equal to theinverse of the coefficient "K." The coefficient K is used as amathematical designation for the thermal conductivity of a material. Itsvalue provides a measurement of the inherent heat transferenceproperties of the material. The coefficient R accordingly represents theinverse of conductivity, or in order words, is a measurement of thethermal resistance or inherent quality of the insulating ability of thematerial. A "high R value" material or device therefore possesses highthermal resistance or insulating ability. The outer wall generallyprovides the majority of the structural support of the building and willbe made of a high strength material.

For example, one of the least expensive and strongest building materialsthat has found extensive use in the construction industry is concrete,which is formed from a mixture comprising a hydraulic cement binder,water and a relatively low cost and high compressive strength aggregatematerial, such as rocks, pebbles and sand. Together these form arelatively high strength, low cost building material. Unfortunately,concrete has the drawback of offering poor insulation compared to highlyinsulating materials such as fiberglass or polymeric foam materials.While an 8 inch slab of concrete has an R value of 0.64, a 1 inch panelof polystyrene has an R value of 5.0. However, these latter materials,while highly insulative, also have the drawback of offering little interms of structural strength or integrity. Although structural wallsmade of cement or masonry can be fitted and even retrofitted with anynumber of insulating materials, including insulating mats or foams thatare sprayed between an inner and outer wall, the insulation material isnot able to impart the most efficient insulation possible due to therequired structural bridging of the outer structural wall with the innerstructural wall.

Such structural bridging is necessary in order for the two-wallstructure to have high strength and integrity and to prevent the twowalls from collapsing together or separating apart during constructionand subsequent use of the building. This has usually been accomplishedthrough the use of metal studs, bolts, or beams. However, cause metal isa very good conductive material (and therefore has very low insulation),such studs, bolts, beams, or other means for structurally bridging thetwo walls together also create a conduit or conductive thermal bridgeacross which heat can readily flow, notwithstanding their beingsurrounded by ample amounts of an insulating material. As a result, heatcan rapidly flow from a relatively warm inside wall to a colder outsidewall during cold weather, for example. Therefore, although an insulatingmaterial may have a relatively high R value, the net R value of the twowalls can often be far less, thus negating or minimizing the effect ofadding additional layers of insulation. Of course, one might construct abuilding having no structural bridges between the inner and outer wallswith the result being a wall having inadequate strength for mostbuilding needs.

In order to overcome these deficiencies some have attempted to pour twoseparate concrete slab walls with a highly insulative layer such aspolystyrene foam sandwiched between the two concrete walls. For example,the following U.S. Patents disclose such a composite wall structure heldtogether using metal tie rods or studs: U.S. Pat. No. 4,393,635 to Long,U.S. Pat. No. 4,329,821 to Long et al., U.S. Pat. No. 2,775,018 toMclaughlin, U.S. Pat. No. 2,645,929 to Jones, and U.S. Pat. No.2,412,744 to Nelson. Unfortunately, as soon as metal studs or connectorsare used to structurally tie together the two concrete walls, the highlyinsulating effect of the polystyrene foam is substantially lost due tothe thermal bridging effect of the highly conductive metal studs orconnectors. Thus, the polystyrene foam or other high R-value insulatingmaterial is unable to impart the full level of insulation possiblebecause of the conductive thermal bridges.

In order to substantially overcome the problems of thermal bridging,others have begun to employ the use of tie rods having a metal portionpassing through the concrete layers and a thermally insulating portionpassing through the insulating layer (e.g., U.S. Pat. No. 4,545,163 toAsselin). Others have developed highly insulative connector rods thatare made entirely from high R-value materials in order to connecttogether the two concrete structural layers while minimizing the thermalbridging effect between the outer concrete layers. For example, U.S.Pat. No. 4,829,733 to Long (hereinafter the "Long '733 Patent")discloses a plastic shear connector for forming an insulated wall havinginner and outer concrete structural layers with highly insulating layerssandwiched therebetween. Although the plastic shear connector describedin the Long '733 Patent has found some use in the construction industry,both the design of the connector described therein as well as the methodfor making such a connector create added materials, manufacturing andlabor costs due to the relatively difficult method of forming theconnector set forth in the Long '733 Patent, as well as the manner inwhich it is used.

For example, the manufacture of the Long '733 Patent connector requiresat least five basic manufacturing steps, and possibly more, due to thematerials used to form the connector, as well as the design of theconnector. First of all, the Long '733 Patent connector includes twoseparate pieces formed by different manufacturing methods and fromdifferent materials which must be fastened together to form the Long'733 Patent connector.

On the one hand, the flat, elongate portion which extends through theentire length of the Long '733 Patent connector is formed from acontinuous fiber, such as glass, graphite or boron, which has beenimpregnated with a polyester vinyl ester epoxy or other suitable polymerbinder. Although no manufacturing process for forming the flat, elongateportion is disclosed within the Long '733 Patent, the most economicaland reliable method of forming a flat, elongate rod having the properdimensions is by pultrusion. Because pultrusion (like extrusion) yieldsarticles of uniform cross section, the flat, elongate portion mustfurther be cut to length and then machined in order to provide thetapered portions that are necessary to retain the connector within thehardened concrete slabs. Hence, three separate manufacturing steps arerequired to create the flat, elongate portion alone.

In addition, the central sleeve portion must be separately molded by,for example, injection molding, and then be separately mounted over thecentral portion of the flat, elongate portion (column 3, lines 2-4). Oneof the purposes of the central sleeve portion is to provide a flangewhich bears on the sidewall of the insulation sheet to prevent the Long'733 Patent connector from penetrating too far or too little within thedifferent layers of the composite wall structure (column 3, lines 4-8).Because the flat, elongate portion is formed by pultrusion, the flangeof the central sleeve portion cannot be formed in one step. Thus, whileproviding a connector having superior insulation and strength, the Long'733 Patent only discloses a shear connector having a very highlyspecialized design and method of manufacture.

The Long '733 Patent also discloses a connector whose design limitationsfurther complicate its use in the manufacture of composite wallstructures. For example, the relatively wide, flat end of the connectorthat is to be inserted through the insulating layer and first concreteslab creates a significant amount of resistance to penetration unlessthe connector is carefully inserted through a hole that is pre-drilledthrough the insulating layer and which is significantly larger indiameter than the greatest width of the flat end of the Long '733 Patentconnector.

In addition, the opposite end of the Long '733 Patent connector that isproximal to the flange has the same flat, narrow dimensions as thedistal end inserted through the insulating layer and first concretelayer. Not only is the flat, narrow proximal end relatively difficult tograb by a technician attempting to force the Long '733 Patent connectorthrough the two layers, but it does not provide a reliable surface uponwhich the connector can receive a strong impact or blow, such as by ahammer or mallet, to aid in the insertion of the connector throughinsulating and first concrete layers.

From the foregoing it is clear that what are needed are improved designsand methods for manufacturing highly insulative composite wallconnectors.

In addition, what are needed are improved designs and methods for makingimproved connector rods that can be molded in a single step and yetprovide means for anchoring the connector within the concrete layerswhile also providing means for positioning the connector within theinsulating layer during the formation of the composite wall structure.

In particular, it would be a vast improvement in the present art toprovide connector rods that could be integrally molded in one stepwithout the need to separately mold an elongate connector shaft havingmeans for retaining the shaft within the outer structural layers and acentral sleeve portion having a flange and an enlarged central diameterfor positioning the connector within the insulating layer.

In addition, what are needed are improved designs and methods formanufacturing improved connector rods that have means for facilitatingtheir penetration through an insulating layer and a first of twostructural layers during the formation of the composite wall structure.

In addition, it would be a tremendous advancement in the art to provideimproved connectors having means for receiving an impact such as from ahammer or mallet, or to aid in gripping the connector, to facilitate thepenetration of the connector rods through the insulating layer and thefirst structural layer.

Such improved designs and methods for manufacturing connector rodshaving the aforesaid features are set forth and claimed herein.

SUMMARY OF THE INVENTION

The present invention relates to improved designs and methods formanufacturing a wall connector used in the manufacture of composite wallstructures. In particular, such connectors can be manufactured in asingle step and may be used in the manufacture of highly insulating wallstructures having two concrete layers between which is sandwiched ahighly insulating material. Such wall connectors prevent or greatlyreduce the flow of heat between the two concrete walls surrounding theinsulative material, and also facilitate their placement within thevarious layers of concrete and insulation material during themanufacturing process of the composite structure. Such insulating wallconnectors can be molded in a single step such as by, for example,injection molding, resin transfer molding, or reaction injectionmolding, thereby eliminating the need to form the connectors in amulti-step fashion as in the Long '733 Patent.

In a preferred embodiment, the connector rod is injection molded from apolycarbonate resin or other high strength resin or moldable plasticmaterial. Another preferred material is a polycarbonate "alloy"consisting of polycarbonate and polybutylene teraphthalate. In somecases, where increased tensile and bending strength are desired,discontinuous fibers such as glass fibers, carbon fibers, mineralfibers, boron fibers, ceramic fibers, and the like may be impregnatedwithin the resin to form a connector rod having increased strength andstiffness. The use of more flexible fibers, such as cellulosic, nylon,or other polymeric fibers would be expected to increase the toughnessand decrease the stiffness of the connector rod. Nevertheless, wherefibers are unnecessary it will be preferable not to use them due totheir increased cost. Whereas in the Long '733 Patent the continuousfibers disclosed therein are the main structural component and aremerely bonded together by the resin, the major structural component ofthe connectors of the present invention is the moldable resin or otherplastic material itself into which discontinuous fibers may beimpregnated. This allows for the connectors of the present invention tobe molded into a wide variety of desired designs having any number ofaccessories or other variations.

In the past, it was believed that appropriate connectors should have atensile strength commensurate with the steel connectors they wereintended to replace. Hence, connectors such as the Long '733 Patentconnector employed continuous fibers of high tensile strength in orderto yield a connector having what was erroneously believed to be theminimum required tensile strength necessary to hold the two concretelayers together.

However, studies carried out by the present inventors have shown thatconnectors formed by pultruding continuous fibers have a tensilestrength far exceeding the maximum required in the formation ofcomposite insulating walls. In fact, the more important strengthvariables are shear strength and bending strength, which also affect thetoughness of the connector rod. The inventors have discovered that byusing an appropriate resinous material such as polycarbonate,polycarbonate-polybutylene teraphthalate alloy, epoxy or other highstrength resins, a connector having more than adequate tensile strengthcan be injection molded in a single step. Because continuous fibers addlittle or nothing to the shear strength and bending strength of theconnector rod they are generally unnecessary. In fact, in the case wherediscontinuous fibers are employed, the random orientation of thediscontinuous fibers would be expected to impart greater shear strength,bending strength and toughness to the connector compared to continuousfibers.

Of equal or greater importance is that the use of resins or othermoldable plastics (whether or not impregnated with discontinuous fibers)allows for an almost endless variety of configurations that can bemolded in a single step. In contrast, the pultrusion methods of the pastallow for only the simplest, most uniform shapes such as cylinders,rectangles, or hexagonal rods, a common feature being that the diameteralong the longitudinal axis is always the same throughout the length ofthe pultruded article. Any variation in shape of a pultruded rodrequires a machining step and/or separate molding or attachment steps toprovide the necessary structural features.

In short, because of the discovery by Applicants that it is the shearstrength and bending strength rather than the tensile strength that arethe more important strength variables, Applicants have taken advantageof the superior manufacturing process of molding a resin in a singlestep to produce a connector rod of greatly reduced cost and improveddesign at the same time. Depending on the performance criteria of thecomposite wall, the frequency of the connectors therein, and the type ofresin or other moldable plastic material, more or less fibers will berequired in order to provide adequate strength properties. In some casesit may be possible to eliminate them altogether.

In a preferred design, the connector rod has a central shaft having atone end a pointed tip which facilitates the entry of the connector rodthrough an insulative material and into a first layer of uncuredconcrete during the manufacture of a composite wall structure. On theopposite end of the connector rod is an enlarged head for receiving theimpact of a hammer or mallet, or the grip of a technician, to facilitatethe penetration of the connector rod through the insulating layer andthe first uncured concrete layer. The combination of the pointed tip atone end and a large elongated head at the opposite end greatlyfacilitates the use of the connector rod in the manufacture of compositewall structures. The pointed tip helps in piercing the material whilethe camming effect of the increasing diameter of the pointed tip helpsto guide the shaft of the connector through the various layers ofmaterial.

Not only is it far quicker and easier for the builder to insert theconnector rods of the present invention through the composite layers,but the connector rods can be inserted through an insulating materialthat has a greatly reduced hole drilled therethrough, or even none atall, due to the pointed surface of the connector rod. In addition, theenlarged head provides greater ease in hammering or malleting theconnector rods through a reduced hole or where no hole through theinsulating material has been provided.

The connector further includes one or more recessed portions at eitherend into which uncured concrete can flow and then harden in order toanchor the connector firmly and reliably within the concrete layers ofthe composite wall structure. For example, a preferred connector has atleast one recess within the central shaft proximal to the pointed tip.The vibrational forces imparted by striking the connector rod with ahammer or mallet (or by manual twisting) facilitate the spreading orflow of the yet uncured concrete into the recess within the centralshaft. In this way, the connector rod is firmly anchored within thefirst concrete slab as it cures.

Toward the other end of the connector rod is a flange or otherprotrusion laterally displaced from the surface of the central shaft,such as a ridge, which comes into abutting contact with the insulatinglayer to prevent the connector rod from being inserted too far into theinsulating layer and first concrete layers. Because of the one-stepinjection molding process this flange or other protrusion can be moldedinto the connector rod in a single step.

After a first structural layer has been poured and is yet substantiallyunhardened, an insulating layer is placed thereon. The insulation layerpreferably includes holes drilled therethrough through which theconnector rod can be inserted. The pointed tip of the connector rodfacilitates penetration of the connector rod through the insulatinglayer and into the first structural layer. Nevertheless, due to thepiercing effect of the pointed tip and the softness of most insulatingmaterials contemplated by the present invention, it may be possible toinsert the connector rods directly through an insulating layer that hasnot been pre-drilled. The flange on the central shaft provides for theinsertion of the connector rod through the insulation layer and firststructural layer until the preferred depth. Thereafter, the secondstructural layer is poured onto the remaining surface of the insulationlayer.

Finally, when the second concrete layer is poured over the surface ofthe insulating material from which protrude the ends of the connectorrods having the enlarged head, the enlarged head, together with theflange or other protrusion, define a second recessed portion into whichthe fresh concrete of the second layer can flow. Upon curing, the headportion and the recess provide for the second end of the shear connectorrod to be locked into place within the cured cement layer. Together,they resist the separation or collapse of the second structural layerrelative to the first structural layer. The first recessed portion ofthe central shaft within the first structural layer provides for both ofthese functions.

From the foregoing, an object of the present invention is to provideimproved designs and methods for manufacturing highly insulativecomposite wall connectors.

A further object and feature of the present invention are improveddesigns and methods for making improved connector rods that can bemolded in a single step, and yet provide means for anchoring theconnector within the structural layers while also providing means forpositioning the connector within the insulating layer during theformation of the composite wall structure.

In addition, another object of the present invention is to provideconnector rods that can be integrally molded in one step without theneed to separately mold an elongate connector shaft having means forretaining the shaft within the outer structural layers, and a centralsleeve portion having a flange and enlarged central diameter forpositioning the connector within the insulating layer.

Another object and feature of the present invention is to provideimproved connector rods that have means for facilitating theirpenetration through an insulating layer and a first of two structurallayers during the formation of the composite wall structure.

Finally, another object of the present invention is to provide improvedconnectors having means for receiving an impact such as from a hammer ormallet, or to aid in gripping the connector, and thereby facilitate thepenetration of the connector rods through the insulating layer and thefirst structural layer.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned from the practice of the invention as setforth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an insulating connector rod having agenerally circular cross-section.

FIG. 2 is a perspective view of the insulative connector rod of FIG. 1with an angled ridge.

FIG. 3 is a perspective view of an insulating connector rod having aslightly elliptical cross-section.

FIG. 4 is a perspective view of an insulating connector rod having asubstantially elliptical cross-section.

FIG. 5 is a perspective view of an insulating connector rod having acruciform cross-section.

FIG. 6A is a front elevational cross-section view of a partiallycompleted composite wall structure.

FIG. 6B is a front elevational cross-section view of a composite wallstructure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to highly insulative connectors orconnector rods having improved design for use in the manufacture ofcomposite wall structures, and methods for the manufacture and use ofsuch connector rods. Such connector rods can be manufactured in a singlestep to yield connectors that have a wide variety of structural featuresand accessories therein. Such connector rods are designed to secure twostructural layers together with a layer of a highly insulating materialsandwiched therebetween. Because the connector rods have a high R value,they prevent or greatly reduce the flow of heat between the two concretewalls compared to metal connectors used in the past. The design of theconnector rod facilitates their use by builders while manufacturing thecomposite wall structure.

The connector rods of the present invention are preferably injectionmolded from any appropriate resin or other high strength plasticmaterial, although they may also be molded by resin transfer molding,reaction injection molding, or any other single step or relativelysimple molding process known in the art. An important criteria is thatthe manufacturing costs of the molding process be commensurate to theoverall cost parameters of the connector rod to be used.

A preferred resinous material is polycarbonate resin because of the easein which it may be injection molded. Another similar resinous materialis polycarbonate-polybutylene teraphthalate alloy, which is lessexpensive than polycarbonate resins. Other resins such as epoxy resins,thermoset plastics, and other high strength, high R-value materials maybe used. An important criteria is to select a resinous material or otherplastic having the desired properties of strength and insulationdepending on the performance criteria of the composite wall structure tobe fabricated.

Although not necessary in many instances, it may be desirable toincorporate within the resinous material or other plastic materialdiscontinuous fibers such as glass fibers, carbon fibers, boron fibers,ceramic fibers, and the like in order to increase the tensile strength,bending strength, and toughness of the connector rod. Discontinuousfibers can also increase the shear strength of the connector rod ifadequately randomly dispersed throughout the resinous or other plasticmaterial. Nevertheless, where fibers are not necessary in order toimpart greater strength or stiffness to the connector rod, it will bepreferable not to use them due to their increased cost.

Because the use of resins or other moldable plastics (whether or notimpregnated with discontinuous fibers) allows for an almost endlessvariety of design configurations that can be molded into a connector rodin a single step, such connector rods can include a wide variety ofstructural features or accessories without increasing the cost ofmanufacture.

Referring to FIG. 1, a preferred design of the connector rod 10 of thepresent invention includes an elongate shaft 12 that is generallycylindrical or ellipsoidal. The connector rod 10 has a penetratingsegment 16 at one end, an impact segment 18 at the opposite end, and amesial segment 20 disposed between the penetrating segment 16 and theimpact segment 18. The mesial segment 20 essentially comprises themiddle section of the elongate shaft 12 although appropriate accessoriesor other design features could be included therein to provide furtherfunctionality.

At the end of the penetrating segment 16 distal to the mesial segment 20is a pointed tip 22. Although the pointed tip 22 has a generally conicalshape as shown in FIG. 1, it can be of any shape so long as it generallyends in a tip having a substantially reduced diameter relative to thediameter of the elongate shaft 12. The pointed tip 22 facilitates entryof the connector rod 10 through an insulating layer and a first layer offresh, unhardened structural material, as set forth more fully below.

In addition, the penetrating segment 16 further includes one or morerecesses 24 disposed between the mesial segment 20 and the area of thepenetrating segment 16 near the pointed tip 22. As set forth more fullybelow, the penetrating segment 16 is intended to substantially penetrateand be anchored within a first structural layer. The recessed portions24 greatly aid in the anchoring and securing of the penetrating segment16 within the first structural layer.

Further up the elongate shaft 12 is the mesial segment 20 which isgenerally of uniform shape, and may be cylindrical or may have across-section of, e.g., an ellipse or cruciform. Near or at the end ofthe mesial segment 20 distal to the penetrating segment 16 is a flange26 or other ridge which acts as a means for orienting the connector rod10 within an insulating layer stacked together with a first structurallayer. The mesial segment 20 is intended to occupy, in a close-fittingmanner, a hole drilled within the insulating layer or formed by thepiercing effect of the pointed tip 22 of the penetrating segment 16 whenthe connector rod 10 is inserted through the insulating layer and into afirst structural layer of yet unhardened material. By definition, then,the length of the mesial segment is generally equal to the thickness ofthe insulating layer.

The flange 26 or other ridge aids in the placement of the connector rod10 at the proper depth through the insulating layer and first structurallayer. Of course, the flange 26 should be oriented at an angle relativeto the elongate shaft 12 which corresponds to the desired angle oforientation of the connector rod 10 through the composite wallstructure. If, for example, the connector is intended to be orientedperpendicular to the surface of the insulating layer (FIG. 6A), theflange 26 would preferably be oriented orthogonally to the surface ofthe elongate shaft 12. However, the flange may be offset at anyappropriate angle.

Further up the elongate shaft, away from the penetrating segment 16 isthe impact segment 18. (FIG. 1.) The impact segment begins at or nearthe flange 26 or other ridge along the elongate shaft 12 and terminatesat an enlarged head 28 disposed at an end of thc impact segment 18distal to the mesial segment 20. The ridge or flange 26 is said to be ator near (or proximal to) the intersection of the mesial segment 20 andimpact segment 18 because of the interplay between the definitions ofthe three connector rod segments and the layers of the composite wallstructure into which the segments will be imbedded, as well as theaccuracy of placement of the connector rods within the layers and thethickness of the ridge or flange 26. One of the purposes of the enlargedhead 28 is to receive an impact force, such as from a hammer or mallet,or to facilitate the gripping of the connector rod 10 during itsinsertion through an insulating layer and a first structural layer. Inaddition, the enlarged head 28 also functions to prevent a secondstructural layer that is formed around the impact segment 18 frompulling away from the first structural layer and insulating layer.

Acting in tandem therewith, the flange 26 or other ridge prevents thesecond structural layer from collapsing toward the first structurallayer. In essence, the enlarged head 28 and flange 26 or other ridgedefine a pseudo-recessed portion 30 within the portion of the elongateshaft 12 therebetween, although the portion of the elongate shaft 12between the enlarged head 28 and flange 26 may have the same diameter asthe rest of the elongate shaft 12 (excluding recesses 24). Because ofthe ease in which the connector rods of the present invention may beinjection molded, the pointed tip 22, the recesses 24, the flange 26,and the enlarged head 28 can be quickly and easily formed within theconnector rod 10 in a single molding step. (Nevertheless, one may wishto incorporate one or more structural features or accessories into theconnector rod using one or more separate molding or forming steps. Inaddition, a freshly demolded connector rod may, if desired, bestructurally altered such as by curving or bending the connector rodwhile still in an unhardened condition.)

In addition to the structural features of the connector rod 10 shown inFIG. 1, reference to FIG. 2 shows that a cammed ridge 32 can beincorporated along the elongate shaft 12 proximal to the intersectionbetween the penetrating segment 16 and the mesial segment 20. Thepurpose of the cammed ridge 32 is to provide means for locking theconnector rod in place once it has been fully inserted through theinsulating layer up to the flange 26.

FIG. 3 shows another alternative embodiment that has substantially thesame structural features as the connector rod 10 shown in FIG. 1, exceptthat the elongate shaft 40 and other features of the connector rod 42have a slightly elliptical cross-section rather than being cylindrical.In most respects however, the connector rod 40 functions in essentiallythe same way as the connector rod 10 of FIG. 1. Although the shape ofthe recesses are different in this embodiment, they perform essentiallythe same anchoring function as the recesses illustrated in FIGS. 1 and2. In fact, the shape or depth of the recess or recesses is relativelyunimportant so long as the recesses provide adequate means for anchoringthe penetrating segment within a first structural layer.

FIG. 4 shows another embodiment of a connector rod of the presentinvention similar to that shown in FIG. 3, except that the elongateshaft 50 of connector rod 52 has an even more exaggerated ellipticalcross-section compared to the connector rod 40 of FIG. 3. Thecross-sectional shape of the elongate shaft and other design features isless important than the functional features themselves. The actualcross-sectional shape may be selected to correspond to the particulardesign and performance criteria of the composite wall structure to bemanufactured. Because the cross-section of the connector rod of FIG. 4is elliptoidal, the pointed tip is more scalloped than conical.

FIG. 5 illustrates yet another embodiment of the present invention inwhich the elongate shaft 60 of the connector rod 62 has a generallycruciform cross-section. Within the spaces defined by the fins of thecruciform structure are ridges 64, which aid in the anchoring of theconnector rod 62 within a first structural layer. As before, a flange 66and an enlarged head 68 help to anchor the connector rod 62 within asecond structural layer.

Reference is now made to FIG. 6A, which shows an integral connector rod10 placed within a front elevational cross-section view of a firststructural layer 70 and an insulating layer 80. In a preferred methodfor manufacturing composite wall structures, a first layer of astructural material is poured into an appropriate form. In general, thefirst structural layer 70 will be a rectangular slab, although it mayalso include other design, ornamental or structural features. The onlylimitation is that it have a thickness or depth great enough to give thestructural layer adequate strength and also the ability to firmly anchorthe penetrating segment 16 of a connector rod 10 placed therein.

The first structural layer 70 may comprise any suitable material whichcan flow when initially cast and then harden to form a generally rigid,structural layer. In a preferred embodiment, the first structural layer70 comprises a concrete material including a hydraulic cement binder,water, an aggregate material and other appropriate admixtures. Concreteis preferred because of its low cost, high strength and ease of castingcompared to other materials. Nevertheless, any appropriate structuralmaterial may be used, such as high strength polymers, resins or othermaterials which can flow when cast and later be hardened.

Before the first structural layer 70 obtains such rigidity that aconnector rod 10 cannot be placed therein without damaging the ultimatestructural integrity and strength of the structural layer, an insulatinglayer 80 is placed adjacent to the exposed side of the first structurallayer 70. The insulating layer may include any appropriate insulatingmaterial, such as polystyrene foam, fiberglass, aerogel, xerogel,xonotlite, seagel, polyisocyanate foam, polyurethane foam,urea-formaldehyde foam, and low density, highly insulating cementitiousmaterials. Such insulating materials are given only by way of example,not by limitation.

The insulating layer 80 preferably includes a plurality of holes drilledor punched therethrough, through which the connector rod 10 of thepresent invention will be inserted. A connector rod 10 is insertedthrough each of the holes within the insulating layer 80 and alsothrough the first structural layer 70 until the flange 26 preventsfurther penetration. Once properly oriented, the penetrating segment 16(FIG. 1) will substantially reside within the first structural layer 70,while the mesial segment 20 will substantially occupy the hole or spacewithin the insulating layer 80 (FIG. 6A). Because of the piercing effectof the pointed tip 22 of the connector rod 10, it may be possible todrill holes having a substantially smaller diameter compared to thediameter of the elongate shaft 12 of the connector rod 10. In somecases, no holes will be required at all.

After the first structural layer 70 has achieved an adequate level ofhardness or strength, a second layer of structural material is pouredover the surface of the insulating layer 80 to form the secondstructural layer 90, as shown in FIG. 6B. The second structural layer 90may also comprise any appropriate material that will initially flow andthen harden to form a substantially rigid structural wall. Nevertheless,concrete is preferred due to its low cost, high strength and ease offormation Although the second structural layer 90 will generally be arectangular slab, it may also include other designs, structural orornamental features. The thickness or depth of the second structurallayer 90 should be such that it completely, or at least substantially,engulfs the enlarged head 28 of the connector rod 10, thereby providingan adequate anchoring effect of the connector rod 10 within the secondstructural layer 90. The flange 26 also aids in preventing the hardenedsecond structural layer 90 from collapsing against the first structurallayer 70.

In some cases it may be desirable to lay a second insulating layer overthe yet unhardened second structural layer, followed by the insertion ofadditional connector rods through the second insulation layer and secondstructural layer. Thereafter, a third structural layer will be cast overthe surface of the second insulating layer as before. Because of thesimplicity of molding the connector rods of the present invention, anadapted connector rod could be molded that would connect all threestructural layers together.

The various connector rods described herein were used in experimentalcomposite wall structures and were found to have more than adequateshear strength to hold together the three layers of the composite wallstructures that were tested. In fact, in all cases when a stress strongenough to cause a failure of the composite wall structure was applied,it was the concrete structural layer that failed in each instance. Theconnector rods were left intact.

From the foregoing, it will be appreciated that the present inventionprovides improved designs and methods for manufacturing highlyinsulative composite wall connectors.

The present invention also provides improved designs and methods formaking improved connector rods that can be molded in a single step, andyet provide means for anchoring the connector rod within the structurallayers, while also providing means for positioning the connector withinthe insulating layer during the formation of the composite wallstructure.

In addition, the present invention provides connector rods that can beintegrally molded in one step without the need to separately mold anelongate connector shaft having means for retaining the shaft within theouter structural layers, and a central sleeve portion having a flangeand enlarged central diameter for positioning the connector within theinsulating layer.

Further, the present invention provides improved connector rods thathave means for facilitating their penetration through an insulatinglayer and a first of two structural layers during the formation of thecomposite wall structure.

Finally, the present invention provides improved connectors having meansfor receiving an impact such as from a hammer or mallet, or to aid ingripping the connector, and thereby facilitate the penetration of theconnector rods through the insulating layer and the first structurallayer.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A connector rod for use in making an insulating compositewall structure including first and second structural layers and aninsulating layer disposed therebetween, the connector rod comprising acured resinous or plastic material having a high thermal resistance, theconnector rod formed by the process comprising the steps of:(1)providing a resinous or plastic material having a high thermalresistance; and (2) molding the resinous or plastic material into apredetermined shape of the connector rod in a single step in order toform the connector rod to have a single continues body such that itincludes:(a) an elongate shaft; (b) a substantially pointed tipprojecting from a first end of the elongate shaft; (c) a second end ofthe elongate shaft opposite the first end, the second end terminating inan enlarged head; (d) means disposed between the first and second endsfor orienting the connector rod within an insulating layer at apredetermined depth; (e) means within the first end for anchoring thefirst end within a first structural layer; and (f) means within thesecond end for anchoring the second end within a second structurallayer; and (3) curing the molded connector rod, thereby forming thearticle of manufacture.
 2. A connector rod as defined in claim 1,wherein the plastic material consists essentially of an epoxy-basedresin.
 3. A connector rod as defined in claim 1, wherein the plasticmaterial consists essentially of a polycarbonate-polybutelineteraphthalate alloy.
 4. A connector rod as defined in claim 1, whereinthe the connector rod is manufactured without any further machining orassembly steps.
 5. A connector rod as defined in claim 1, the methodfurther including the step of reshaping the molded connector rod from apredetermined shape into a second shape having substantially the samefunctional features as the predetermined shape.
 6. A connector rod asdefined in claim 1, wherein the resinous material includes discontinuousfibers dispersed therein.
 7. A connector rod as defined in claim 6,wherein in the discontinuous fibers are selected from the groupconsisting of glass fibers, carbon fibers, boron fibers, ceramic fibers,and mixtures thereof.
 8. A connector rod as defined in claim 1, whereinthe plastic material comprises a high strength resin.
 9. A connector rodas defined in claim 1, wherein the plastic material comprises athermoset plastic.
 10. A connector rod as defined in claim 1, whereinthe means for orienting the connector rod within an insulating layerincludes a flange disposed on a surface of the elongate shaft.
 11. Aconnector rod as defined in claim 1, wherein the means within the firstend for anchoring the first end within a first structural layercomprises a recessed portion within the first end of the elongate shaft.12. A connector rod as defined in claim 1, wherein the means within thesecond end for anchoring the second end within a second structural layercomprises the enlarged head.
 13. A connector rod as defined in claim 1,wherein the elongate shaft has a generally circular cross-section.
 14. Aconnector rod as defined in claim 1, wherein the elongate shaft has agenerally elliptical cross-section.
 15. A connector rod as defined inclaim 1, wherein the elongate shaft has a generally cruciformcross-section.
 16. A connector rod as defined in claim 1, wherein thesubstantially pointed tip includes structure for facilitatingpenetration of the connector rod through an insulating layer.
 17. Aconnector rod as defined in claim 1, wherein the molding step isselected from the group consisting of injection molding, resin transfermolding, and reaction injection molding.
 18. A connector rod for use incombination with an insulating composite wall structure including firstand second structural layers comprising a hardenable material and aninsulating layer having a high thermal resistance disposed therebetween,the connector rod comprising a molded resinous or plastic materialhaving a high thermal resistance, and being rod formed by the processcomprising the steps of:(1) providing a resinous or plastic materialhaving a high thermal resistance; and (2) molding the resinous orplastic material into a predetermined shape of the connector rod to forma single continues body such that it includes:(a) an elongate shafthaving a penetrating segment, an impact segment, and a mesial segmenttherebetween; (b) a substantially pointed tip at an end of thepenetrating segment distal to the mesial segment for penetrating theinsulating layer and the first structural layer while yet in anunhardened state; (c) an enlarged head at an end of the impact segmentdistal to the mesial segment, wherein the enlarged head is embeddedwithin the structural layer when used in making the composite wallstructure; (d) means for orienting the connector rod within theinsulating layer at a predetermined depth; (e) means within thepenetrating segment for anchoring the penetrating segment within thefirst structural layer when substantially hardened; and (f) means withinthe impact segment for anchoring the impact segment within the secondstructural layer when substantially hardened, wherein the connector rodhas a strength and configuration such that when used in making thecomposite wall structure in which the insulating layer is disposedbetween the first and second structural layers in a desiredconfiguration the connector rod will remain firmly embedded within thestructural layers while substantially retaining the first and secondstructural layers and the insulating layer in the desired configuration,the connector rod having a configuration such that when the connectorrod is embedded within the composite wall structure the orienting meansdoes not completely penetrate the insulating layer.
 19. A connector rodas defined in claim 18, wherein the connector rod is molded in a singlestep using a process selected from a group consisting of injectionmolding, resin transfer molding, and reaction injection molding.
 20. Aconnector rod for use in making an insulating composite wall structureincluding first and second structural layers and an insulating layerdisposed therebetween, the connector rod comprising a substantiallycured resinous or plastic material having a high thermal resistance andbeing formed by the process comprising the steps of:(1) providing aresinous or plastic material having a high thermal resistance; and (2)molding the resinous or plastic material into a predetermined shape ofthe connector rod to form a single continues body in a single step usinga process selected from the group consisting of injection molding, resintransfer molding, and reaction injection molding, the connector rodbeing thereby molded to include:(a) an elongate shaft having apenetrating segment, an impact segment, and a mesial segmenttherebetween; (b) a substantially pointed tip at an end of thepenetrating segment distal to the mesial segment for penetrating aninsulating layer and a first structural layer while the first structurallayer is yet in an unhardened state; (c) an enlarged head at an end ofthe impact segment distal to the mesial segment, wherein the enlargedhead becomes embedded within a second structural layer when used inmaking a composite wall structure, thereby anchoring the impact segmentwithin the second structural layer; (d) a flange disposed on a surfaceof the elongate shaft proximal to where the mesial segment and theimpact segment intersect; and (e) a recessed portion within thepenetrating segment for anchoring the penetrating segment within a firststructural layer when substantially hardened.